1. Field of the Invention
The present invention relates to a boat propulsion device including a catalyst, and relates to a float position determining method.
2. Description of the Related Art
A boat propulsion device, including a catalyst disposed inside an exhaust pipe, is known (e.g., see Japan Laid-open Patent Application Publication No. JP-A-2011-190704). Such a boat propulsion device includes an internal tank and a fuel injection device. The internal tank temporarily stores a fuel transferred thereto from an external tank mounted to a vessel body. The fuel injection device is configured to inject the fuel stored in the internal tank into an engine.
However, the boat propulsion device described in JP-A-2011-190704 is configured such that an air-fuel ratio within a cylinder enters an over-lean state and a misfire is caused when a fuel shortage is caused in the internal tank in accordance with a fuel shortage in the external tank. In this case, if the fuel, leaking out of the engine to the exhaust pipe, ignites by making contact with a high-temperature catalyst, and thereby, the catalyst might be overheated.